除非我向后压或刷新购物车＆amp; E/Recyclerview：无适配器；跳过布局

Question

我的情况是，每当我执行这些活动时，例如添加，删除 所选项目数量时，直到我按下后面按钮或刷新购物车页面之前，购物车才自动更新。

应该为RM27，因为有3个数量，但是直到我按下后面按钮或刷新购物车之前，它不会自动更新自身。

myfoodAdapter

public class MyFoodAdapter extends RecyclerView.Adapter<MyFoodAdapter.MyFoodViewHolder> {



    private Context context;
    private List<FoodModel> foodModelList;
    private ICartLoadListener iCartLoadListener;

    public MyFoodAdapter(Context context, List<FoodModel> foodModelList, ICartLoadListener iCartLoadListener) {
        this.context = context;
        this.foodModelList = foodModelList;
        this.iCartLoadListener = iCartLoadListener;
    }

    @NonNull
    @Override
    public MyFoodViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new MyFoodViewHolder(LayoutInflater.from(context).inflate(R.layout.layout_food_item,parent,false));
    }

    @Override
    public void onBindViewHolder(@NonNull MyFoodViewHolder holder, int position) {
        Glide.with(context)
                .load(foodModelList.get(position).getImage())
                .into(holder.imageView);
        holder.txtPrice.setText(new StringBuilder("RM").append(foodModelList.get(position).getPrice()));
        holder.txtName.setText(new StringBuilder().append(foodModelList.get(position).getName()));

        holder.setListener((view, adapterPosition) -> {
            addToCart(foodModelList.get(position));
        });

    }

    private void addToCart(FoodModel foodModel) {
        DatabaseReference userCart = FirebaseDatabase
                .getInstance()
                .getReference("Cart")
                .child("UNIQUE_USER_ID"); //In other project, you will add user id here

        userCart.child(foodModel.getKey())
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot snapshot) {
                        if(snapshot.exists()) //If user already have item in cart ,  just update quantity and totalprice
                        {
                            CartModel cartModel = snapshot.getValue(CartModel.class);
                            cartModel.setQuantity(cartModel.getQuantity()+1);
                            Map<String,Object>updateData = new HashMap<>();
                            updateData.put("quantity", cartModel.getQuantity());
                            updateData.put("totalPrice",cartModel.getQuantity()*Float.parseFloat(cartModel.getPrice()));

                            userCart.child(foodModel.getKey())
                                    .updateChildren(updateData)
                                    .addOnSuccessListener(unused -> {
                                        iCartLoadListener.onCartLoadFailed("Add to Cart Success");
                                    })
                                    .addOnFailureListener(e -> iCartLoadListener.onCartLoadFailed(e.getMessage()));

                        }
                        else  //If item is not in the cart, add new
                        {
                            CartModel cartModel = new CartModel();
                            cartModel.setName(foodModel.getName());
                            cartModel.setImage(foodModel.getImage());
                            cartModel.setKey(foodModel.getKey());
                            cartModel.setPrice(foodModel.getPrice());
                            cartModel.setQuantity(1);
                            cartModel.setTotalPrice(Float.parseFloat(foodModel.getPrice()));

                            userCart.child(foodModel.getKey())
                                    .setValue(cartModel)
                                    .addOnSuccessListener(unused -> {
                            iCartLoadListener.onCartLoadFailed("Add to Cart Success");
                        })
                                    .addOnFailureListener(e -> iCartLoadListener.onCartLoadFailed(e.getMessage()));
                        }
                        EventBus.getDefault().postSticky(new MyUpdateCartEvent());
                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError error) {
                        iCartLoadListener.onCartLoadFailed(error.getMessage());
                    }
                });

    }

    @Override
    public int getItemCount() {
        return foodModelList.size();
    }

    public class MyFoodViewHolder extends  RecyclerView.ViewHolder implements View.OnClickListener {
        @BindView(R.id.imageView)
        ImageView imageView;
        @BindView(R.id.txtName)
        TextView txtName;
        @BindView(R.id.txtPrice)
        TextView txtPrice;

        IRecyclerViewClickListener listener;
        public void setListener(IRecyclerViewClickListener listener)
        {
            this.listener = listener;
        }

        private Unbinder unbinder;
        public MyFoodViewHolder(@NonNull View itemView) {
            super(itemView);
            unbinder = ButterKnife.bind(this,itemView);
            itemView.setOnClickListener(this);
        }

        public void onClick(View v){
            listener.onRecyclerClick(v,getAdapterPosition());
        }
    }
}

cart.class

public class Cart extends AppCompatActivity implements IFoodLoadListener, ICartLoadListener {
    @BindView(R.id.recycler_food)
    RecyclerView recyclerfood;
    @BindView(R.id.mainLayout)
    RelativeLayout mainLayout;
    @BindView(R.id.badge)
    NotificationBadge badge;
    @BindView(R.id.btnCart)
    FrameLayout btnCart;

    IFoodLoadListener foodLoadListener;
    ICartLoadListener cartLoadListener;

    @Override
    protected void onStart(){
        super.onStart();
        EventBus.getDefault().register(this);
    }

    @Override
    protected void onStop() {
        if (EventBus.getDefault().hasSubscriberForEvent(MyUpdateCartEvent.class))
            EventBus.getDefault().removeStickyEvent(MyUpdateCartEvent.class);
        EventBus.getDefault().unregister(this);
        super.onStop();

    }

    @Subscribe(threadMode = ThreadMode.MAIN,sticky = true)
    public void onUpdateCart(MyUpdateCartEvent event)
    {
        countCartItem();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cart);

        init();
        loadFoodFromFirebase();
        countCartItem();
    }

    private void loadFoodFromFirebase() {
        List<FoodModel> foodModels = new ArrayList<>();
        FirebaseDatabase.getInstance()
                .getReference("Food")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot snapshot) {
                        if (snapshot.exists())
                        {
                            for (DataSnapshot foodSnapshot:snapshot.getChildren())
                            {
                                FoodModel foodModel = foodSnapshot.getValue(FoodModel.class);
                                foodModel.setKey(foodSnapshot.getKey());
                                foodModels.add(foodModel);
                            }
                            foodLoadListener.onFoodLoadSuccess(foodModels);
                        }
                        else
                            foodLoadListener.onFoodLoadFailed("Cannot find food");
                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError error) {
                        foodLoadListener.onFoodLoadFailed(error.getMessage());
                    }
                });
    }

    private void init(){
        ButterKnife.bind(this);

        foodLoadListener = this;
        cartLoadListener = this;

        GridLayoutManager gridLayoutManager = new GridLayoutManager(this,2);
        recyclerfood.setLayoutManager(gridLayoutManager);
        recyclerfood.addItemDecoration(new SpaceItemDecoration());

        btnCart.setOnClickListener(v -> startActivity(new Intent(this,CartActivity.class)));
    }


    @Override
    public void onFoodLoadSuccess(List<FoodModel> foodModelList) {
        MyFoodAdapter adapter = new MyFoodAdapter(this,foodModelList,cartLoadListener);
        recyclerfood.setAdapter(adapter);
    }

    @Override
    public void onFoodLoadFailed(String message) {
        Snackbar.make(mainLayout,message,Snackbar.LENGTH_LONG).show();
    }

    @Override
    public void onCartLoadSuccess(List<CartModel> cartModelList) {

        int cartSum = 0;
        for(CartModel cartModel : cartModelList)
            cartSum += cartModel.getQuantity();
        badge.setNumber(cartSum);

    }

    @Override
    public void onCartLoadFailed(String message) {
        Snackbar.make(mainLayout,message,Snackbar.LENGTH_LONG).show();
    }

    @Override
    protected void onResume(){
        super.onResume();
        countCartItem();
    }

    private void countCartItem() {
        List<CartModel> cartModels = new ArrayList<>();
        FirebaseDatabase
                .getInstance().getReference("Cart")
                .child("UNIQUE_USER_ID")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot snapshot) {
                        for(DataSnapshot cartSnapshot:snapshot.getChildren())
                        {
                            CartModel cartModel = cartSnapshot.getValue(CartModel.class);
                            cartModel.setKey(cartSnapshot.getKey());
                            cartModels.add(cartModel);
                        }
                        cartLoadListener.onCartLoadSuccess(cartModels);
                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError error) {
                        cartLoadListener.onCartLoadFailed(error.getMessage());
                    }
                });
    }
}

cartactivity.java

    @BindView(R.id.recycler_cart)
    RecyclerView recyclerCart;
    @BindView(R.id.mainLayout)
    RelativeLayout mainLayout;
    @BindView(R.id.btnBack)
    ImageView btnBack;
    @BindView(R.id.txtTotal)
    TextView txtTotal;

    ICartLoadListener cartLoadListener;

    @Override
    protected void onStop() {
        if (EventBus.getDefault().hasSubscriberForEvent(MyUpdateCartEvent.class))
            EventBus.getDefault().removeStickyEvent(MyUpdateCartEvent.class);
        EventBus.getDefault().unregister(this);
        super.onStop();

    }

    @Subscribe(threadMode = ThreadMode.MAIN,sticky = true)
    public void onUpdateCart(MyUpdateCartEvent event)
    {
        loadCartFromFirebase();
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_cart2);

        init();
        loadCartFromFirebase();
        
    }

    private void loadCartFromFirebase() {
        List<CartModel> cartModels = new ArrayList<>();
        FirebaseDatabase.getInstance()
                .getReference("Cart")
                .child("UNIQUE_USER_ID")
                .addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot snapshot) {
                        if (snapshot.exists())
                        {
                            for(DataSnapshot cartSnapShot :snapshot.getChildren())
                            {
                                CartModel cartModel = cartSnapShot.getValue(CartModel.class);
                                cartModel.setKey(cartSnapShot.getKey());
                                cartModels.add(cartModel);
                            }
                            cartLoadListener.onCartLoadSuccess(cartModels);
                        }
                        else
                            cartLoadListener.onCartLoadFailed("Cart empty");
                    }

                    @Override
                    public void onCancelled(@NonNull DatabaseError error) {
                        cartLoadListener.onCartLoadFailed(error.getMessage());
                    }
                });
    }

    public void init(){
        ButterKnife.bind(this);

        cartLoadListener = this;
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recyclerCart.setLayoutManager(layoutManager);
        recyclerCart.addItemDecoration(new DividerItemDecoration(this,layoutManager.getOrientation()));

        btnBack.setOnClickListener(v ->finish());
    }

    @Override
    public void onCartLoadSuccess(List<CartModel> cartModelList) {
        double sum = 0;
        for (CartModel cartModel : cartModelList)
        {
            sum+=cartModel.getTotalPrice();
        }
        txtTotal.setText(new StringBuilder("RM").append(sum));
        MyCartAdapter adapter =  new MyCartAdapter(this,cartModelList);
        recyclerCart.setAdapter(adapter);
    }

    @Override
    public void onCartLoadFailed(String message) {
        Snackbar.make(mainLayout,message,Snackbar.LENGTH_LONG).show();
    }
}

以下是mycartadapter.java

public class MyCartAdapter extends RecyclerView.Adapter<MyCartAdapter.MyCartViewHolder> {

    private Context context;
    private List<CartModel> cartModelList;

    public MyCartAdapter(Context context, List<CartModel> cartModelList) {
        this.context = context;
        this.cartModelList = cartModelList;
    }

    @NonNull
    @Override
    public MyCartViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new MyCartViewHolder(LayoutInflater.from(context)
        .inflate(R.layout.layout_cart_item,parent,false));
    }

    @Override
    public void onBindViewHolder(@NonNull MyCartViewHolder holder, int position) {
        Glide.with(context)
                .load(cartModelList.get(position).getImage())
                .into(holder.imageView);
        holder.txtPrice.setText(new StringBuilder("RM").append(cartModelList.get(position).getPrice()));
        holder.txtName.setText(new StringBuilder().append(cartModelList.get(position).getName()));
        holder.txtQuantity.setText(new StringBuilder().append(cartModelList.get(position).getQuantity()));

    //Event
        holder.btnMinus.setOnClickListener(v -> {
            minusCartItem(holder,cartModelList.get(position));
        });
        holder.btnPlus.setOnClickListener(v -> {
            plusCartItem(holder,cartModelList.get(position));
        });

        holder.btnDelete.setOnClickListener(v -> {
            AlertDialog dialog = new AlertDialog.Builder(context)
                    .setTitle("Delete Item")
                    .setMessage("Do you wish to delete the item?")
                    .setNegativeButton("CANCEL", (dialog1, which) -> dialog1.dismiss())
                    .setPositiveButton("OK", (dialog12, which) -> {

                        //Temp remove
                        notifyItemRemoved(position);

                        deleteFromFirebase(cartModelList.get(position));
                        dialog12.dismiss();
                    }).create();
            dialog.show();
                });

    }

    private void deleteFromFirebase(CartModel cartModel) {
        FirebaseDatabase.getInstance()
                .getReference("Cart")
                .child("UNIQUE_USER_ID")
                .child(cartModel.getKey())
                .removeValue()
                .addOnSuccessListener(unused -> EventBus.getDefault().postSticky(new MyUpdateCartEvent()));
    }

    private void plusCartItem(MyCartViewHolder holder, CartModel cartModel) {
        cartModel.setQuantity(cartModel.getQuantity()+1);
        cartModel.setTotalPrice(cartModel.getQuantity()*Float.parseFloat(cartModel.getPrice()));

        holder.txtQuantity.setText(new StringBuilder().append(cartModel.getQuantity()));
        updateFirebase(cartModel);
    }

    private void minusCartItem(MyCartViewHolder holder, CartModel cartModel) {
        if (cartModel.getQuantity() > 1)
        {
            cartModel.setQuantity(cartModel.getQuantity()-1);
            cartModel.setTotalPrice(cartModel.getQuantity()*Float.parseFloat(cartModel.getPrice()));

            //Update quantity
            holder.txtQuantity.setText(new StringBuilder().append(cartModel.getQuantity()));
            updateFirebase(cartModel);
        }
    }

    private void updateFirebase(CartModel cartModel)
    {
        FirebaseDatabase.getInstance()
                .getReference("Cart")
                .child("UNIQUE_USER_ID")
                .child(cartModel.getKey())
                .setValue(cartModel)
                .addOnSuccessListener(unused ->EventBus.getDefault().postSticky(new MyUpdateCartEvent()));
    }

    @Override
    public int getItemCount() {
        return cartModelList.size();
    }

    public class MyCartViewHolder extends RecyclerView.ViewHolder
    {
        @BindView(R.id.btnMinus)
        ImageView btnMinus;
        @BindView(R.id.btnPlus)
        ImageView btnPlus;
        @BindView(R.id.btnDelete)
        ImageView btnDelete;
        @BindView(R.id.imageView)
        ImageView imageView;
        @BindView(R.id.txtName)
        TextView txtName;
        @BindView(R.id.txtPrice)
        TextView txtPrice;
        @BindView(R.id.txtQuantity)
        TextView txtQuantity;

        Unbinder unbinder;
        public MyCartViewHolder(@NonNull View itemView) {
            super(itemView);
            unbinder = ButterKnife.bind(this,itemView);
        }
    }
}

更新：我得到了此新错误E/Recyclerview：无适配器；跳过布局